Connector systems are known which interconnect the electrical lighting system of a towing vehicle with the electrical lighting system of a towed vehicle. The connector systems provide appropriate brake, turn signal and running lamp operation for the towed vehicle. The systems differ slightly depending upon the type of towing vehicle used. Some connector systems have an electrical connector interposed within the electrical lighting system of the towing vehicle and coupled to a harness connector system extending between the towing vehicle and the towed vehicle.
In a motor home for example, the factory installs electrical wiring for the electrical lighting system as original equipment. A T-shaped connector can be selectively interposed within the electrical lighting system of the motor home to provide a tap for electrical power to a towed vehicle, such as a small car or truck. For example, a T-shaped connector manufactured by the assignee of the present invention under the trademark LITE MATE Vehicle Connector can be interposed between a male and female plug in the electrical lighting system of the towing vehicle. The T-shaped connector has a plug-in tap connection configured to receive one end of a harness manufactured by the assignee under the trademark LITE MATE Trailer Connector. The LITE MATE Trailer Connector has a plug-in connector to receive a LITE MATE Wiring Harness. The harness extends along the length of the towed vehicle and has a plug-in connector to receive a LITE MATE Split Wire Vehicle Connector. The vehicle connector can be wired at its other end directly to the filaments in the brake, turn signal and running lamps on the towed vehicle.
The connector system thereby connects the electrical lighting system of the towing vehicle directly with the brake, turn signal and running lamps on the towed vehicle. The lamps on the towed vehicle, however, are also integrally connected within the electrical lighting system of the towed vehicle. Accordingly, electrical signals from the towing vehicle, in the form of electrical feedback, can be applied to the electrical lighting system of the towed vehicle if the systems are not properly isolated, particularly through the turn signal switching elements in the towed vehicle. This feedback can produce unwanted results in the towed vehicle, such as simultaneous illumination of all turn signal lights in the towed vehicle when only the left or right turn signal light on the towing vehicle is illuminated.
Certain types of feedback-preventing circuits for vehicles have been developed, such as is shown in U.S. patent application Ser. No. 07/579,151, filed Sep. 6, 1990, and assigned to the assignee of the present invention. The '151 application shows an adaptor circuit interposed between the electrical lighting system of the towing vehicle and the electrical lighting system of the towed vehicle. The adaptor circuit includes complimentary metal oxide semiconductor (CMOS) exclusive OR integrated circuits (IC) for providing logic functions for the brake and turn signal lights, and an isolation network comprising a series of LED's and phototransistors for preventing feedback to the electrical lighting system of the towing vehicle. However, this circuit is primarily designed to protect the towing vehicle from feedback from a towed vehicle, and is not designed to isolate the turn signal switching elements in a towed vehicle from feedback from a towing vehicle.
Other types of feedback-preventing circuits have been developed, such as an isolator block hard-wired within the electrical lighting system of the towed vehicle to prevent feedback. However, such hard-wiring of an isolation block requires selecting the correct wires in the towed vehicle, cutting these wires, and making appropriate electrical splices and/or connections. This hard-wiring can be inconvenient, time consuming, and requires care and experience in connecting the isolation block within the electrical system of the towed vehicle.